African American (AA) urban adolescents are one of the groups at greatest risk of exposure to HIV, and impoverished urban youth show high rates of other risk behaviors, including drug use, alcohol abuse, and externalizing behaviors. This study is guided by a bioecological model that integrates neighborhood and genetic factors as predictors of a cluster of HIV risk behaviors. Ur specific aims are to: test a bioecological model of HIV risk behaviors among impoverished AA youth; (2) identify mediators and moderators of genes and neighborhoods on a cluster of HIV risk behaviors among impoverished AA youth; (3) conduct all of the research and dissemination of findings according to the highest bioethical standards and in service to the participating community. In order to accomplish these aims, this proposal takes advantage of a natural experiment in which federal housing funds were recently used to relocate a sample of AA youth living in impoverished public housing to more advantaged neighborhoods. In addition to this treatment condition, two natural control groups exist: (1) youth living in other public housing neighborhoods that are equivalent on census measures of poverty and youth self-reported HIV risk behaviors; (2) youth that relocated to similarly disadvantaged neighborhoods. What makes this natural experiment particularly exceptional is that all of these youth (N = 637, ages 14-18) are participants in our ongoing Mobile Youth Survey (MYS), which provides multiple waves of pre-relocation youth self-report data on HIV risk behaviors and neighborhood quality. To complement and extend the MYS database, we will gather detailed assessments of sexual risk taking, substance use, externalizing behaviors, neighborhood risks and resources, family factors, and personality from youth and their primary caregiver. We will also collect DNA from youth and genotype candidate neurotransmitter genes related to the cluster of HIV risk behaviors.. We will obtain for the first time local and federal crime and poverty data. All data collection and dissemination of findings will be performed with consultation from bioethicists and a community advisory board to assure that the highest ethical standards are met at all stages of the research. The immediate goal of this basic research project is to identify bioecological processes involved in a cluster of HIV risk behaviors. The long-term goal is to use these data to develop biological, behavioral, structural, or multilevel interventions for urban, impoverished adolescents highly vulnerable to HIV.